# Deprecation HTTP Header Field (RFC 9745)

**Canonical:** https://apis.io/apis/sunset-header/deprecation-header/  
**Provider:** Sunset Header — https://apis.io/providers/sunset-header/  
**Documentation:** https://www.rfc-editor.org/rfc/rfc9745.html

Deprecation HTTP Header Field (RFC 9745) is one of 2 APIs that [Sunset Header](https://apis.io/providers/sunset-header/) publishes on the [APIs.io](https://apis.io/) network. Tagged areas include HTTP Headers, API Deprecation, RFC 9745, Deprecation, and API Lifecycle. The published artifact set on APIs.io includes API documentation.

RFC 9745 defines the Deprecation HTTP response header field, which signals to clients that a resource has been or will be deprecated. It complements the Sunset header by marking the start of the deprecation lifecycle. The header value is a structured date (Unix timestamp per RFC 9651). The Sunset timestamp, if present, must not be earlier than the Deprecation timestamp.

## Machine-readable artifacts (2)

- **Documentation** — https://www.rfc-editor.org/rfc/rfc9745.html
- **Specification** — https://datatracker.ietf.org/doc/html/rfc9745

## Other Sunset Header APIs (1)

- [Sunset Header (RFC 8594)](https://apis.io/apis/sunset-header/sunset-header/)

## Tags

HTTP Headers, API Deprecation, RFC 9745, Deprecation, API Lifecycle

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Profiled by [API Evangelist](https://apievangelist.com) and published on [APIs.io](https://apis.io/apis/sunset-header/deprecation-header/). The API's provider profile, Kin Score and agent-readiness rating are at https://apis.io/providers/sunset-header/.